.\" $OpenBSD: ASN1_BIT_STRING_set.3,v 1.4 2023/07/28 05:53:10 tb Exp $
.\"
.\" Copyright (c) 2021 Ingo Schwarze <schwarze@openbsd.org>
.\"
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.Dd $Mdocdate: July 28 2023 $
.Dt ASN1_BIT_STRING_SET 3
.Os
.Sh NAME
.Nm ASN1_BIT_STRING_set ,
.Nm ASN1_BIT_STRING_set_bit ,
.Nm ASN1_BIT_STRING_get_bit
.Nd ASN.1 BIT STRING accessors
.Sh SYNOPSIS
.In openssl/asn1.h
.Ft int
.Fo ASN1_BIT_STRING_set
.Fa "ASN1_BIT_STRING *bitstr"
.Fa "unsigned char *data"
.Fa "int len"
.Fc
.Ft int
.Fo ASN1_BIT_STRING_set_bit
.Fa "ASN1_BIT_STRING *bitstr"
.Fa "int bitnumber"
.Fa "int set"
.Fc
.Ft int
.Fo ASN1_BIT_STRING_get_bit
.Fa "ASN1_BIT_STRING *bitstr"
.Fa "int bitnumber"
.Fc
.Sh DESCRIPTION
.Fn ASN1_BIT_STRING_set
sets the length attribute of
.Fa bitstr
to
.Fa len
and copies that number of bytes from
.Fa data
into
.Fa bitstr ,
overwriting any previous data, by merely calling
.Xr ASN1_STRING_set 3 .
This function does no validation whatsoever.
In particular, it neither checks that
.Fa bitstr
is actually of the type
.Dv V_ASN1_BIT_STRING
nor, even if it is, that the
.Fa data
and
.Fa len
arguments make sense for this particular bit string.
.Pp
If the
.Fa set
argument is non-zero,
.Fn ASN1_BIT_STRING_set_bit
sets the bit with the given
.Fa bitnumber
in the
.Fa bitstr ;
otherwise, it clears that bit.
A
.Fa bitnumber
of 0 addresses the most significant bit in the first data byte of
.Fa bitstr ,
7 the least significant bit in the same byte,
8 the most significant bit in the second data byte, and so on.
.Pp
If setting a bit is requested beyond the last existing data byte,
additional bytes are added to the
.Fa bitstr
as needed.
After clearing a bit, any trailing NUL bytes are removed from the
.Fa bitstr .
.Pp
.Fn ASN1_BIT_STRING_get_bit
checks that the bit with the given
.Fa bitnumber
is set in
.Fa bitstr .
.Sh RETURN VALUES
.Fn ASN1_BIT_STRING_set
returns 1 on success or 0 if memory allocation fails or if
.Fa data
is
.Dv NULL
and
.Fa len
is \-1 in the same call.
.Pp
.Fn ASN1_BIT_STRING_set_bit
returns 1 on success or 0 if
.Fa bitstr
is
.Dv NULL
or if memory allocation fails.
.Pp
.Fn ASN1_BIT_STRING_get_bit
returns 1 if the bit with the given
.Fa bitnumber
is set in the
.Fa bitstr
or 0 if
.Fa bitstr
is
.Dv NULL ,
if
.Fa bitnumber
points beyond the last data byte in
.Fa bitstr ,
or if the requested bit is not set.
.Sh SEE ALSO
.Xr ASN1_BIT_STRING_new 3 ,
.Xr ASN1_STRING_set 3 ,
.Xr d2i_ASN1_BIT_STRING 3
.Sh HISTORY
.Fn ASN1_BIT_STRING_set
first appeared in SSLeay 0.6.5.
.Fn ASN1_BIT_STRING_set_bit
and
.Fn ASN1_BIT_STRING_get_bit
first appeared in SSLeay 0.9.0.
These functions have been available since
.Ox 2.4 .
